Cathodic arc deposition (CAT ARC) or Arc-physical vapor deposition (Arc-PVD) is a physical vapor deposition technique in which an electric arc is used to vaporize material from a cathode target. The vaporized material then condenses on a substrate, forming a thin film. The technique can be used to deposit metallic, ceramic, and composite films.
The arc evaporation process begins with the striking of a high current, low voltage arc on the surface of a cathode (known as the target) that gives rise to a small (usually a few micrometers wide), highly energetic emitting area known as a cathode spot. The localized temperature at the cathode spot is extremely high (around 15,000° C.), which results in a high velocity (10 km/s) jet of vaporized cathode material, leaving a crater behind on the cathode surface. The cathode spot is only active for a short period of time, then it self-extinguishes and re-ignites in a new area close to the previous crater. This behavior causes the apparent motion of the arc.
As the arc is basically a current carrying conductor, it can be influenced by the application of an electromagnetic field, which in practice is used to rapidly move the arc over the entire surface of the cathode target, so that the total surface of the cathode surface is eroded over time.
The arc has an extremely high power density resulting in a high level of ionization (30-100%), multiple charged ions, neutral particles, clusters and macro-particles (droplets). If a reactive gas is introduced during the evaporation process, dissociation, ionization and excitation can occur during interaction with the ion flux and a compound film will be deposited.
Cathodic arc deposition is used in the production of coatings on gas turbine engine parts such as airfoil blades. Current practice is to use hardware such as fasteners to hold parts in place during the coating cycle, and has been limited to coating one blade at a time. Hardware needs to be cleaned after each use, adding to the time required to coat a part.